Following a massive accident at the Fukushima reactor, hit by a tsunami in 2011, Japan said it would shut down 11 nuclear reactors, although it has put two back on stream this year.
Areva was involved in the Fukushima clean-up, but that reactor is not covered by the new agreement, the French group said in a statement.
It has been working with Hitachi to improve Japanese reactors' safety for the past two years.
Areva's role will now be to participate in preliminary studies for dismantling boiling-water reactors.
The resource-poor nation's energy bill has soared since it was forced to turn to fossil-fuel imports to plug the gap.
But the Japanese public remains wary of atomic power, and Abe's push has prompted rare protests and damaged his popularity.